Proposals in many technical standards, such as the Third Generation Partnership Project (3GPP) Long Term Evolution (LTE), narrow-band Internet of Things (NB-IoT), and fifth generation (5G) have raised the possibility of some form of connection-free burst transmissions between a user equipment (UE) and an entity in a communications network (or simply, the network). Generally, these techniques rely on end-to-end security between the UE and a non-access stratum (NAS) context maintained for the UE in a core network node, such as a mobility management entity (MME), to avoid the overhead associated with establishing and maintaining an access stratum (AS) context for the UE at an access node, such as a base station or evolved NodeB (eNB).
Because the NAS context is persistent across instances of the burst transmission, the state information of the NAS context needs to remain synchronized between the UE and the network, not only during a single transmission but also after the burst transmission is complete. In particular, when information from the NAS context (e.g., a NAS sequence number) is used as a cryptosync, the information must remain reliably synchronized or else incorrect decryption will occur. The loss of synchronization may not be detectable, leading to the delivery of garbage data to the application layer. The synchronization requirement results in a need for reliable delivery, e.g., by using an automatic repeat request (ARQ) mechanism in Layer 2.